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Biomedical subjects

M Alegre

Publications and source records attributed to M Alegre.

At least 55 records · Page 3Linked to original sources
PubMed1990

Hypothermia and hypoglycemia induced by anti-CD3 monoclonal antibody in mice: role of tumor necrosis factor.

The possible involvement of tumor necrosis factor-alpha (TNF) in the metabolic disturbances induced by anti-CD3 monoclonal antibodies (mAb) was analyzed in DBA/2 mice injected with 50 micrograms of the anti-murine CD3 mAb 145-2C11. First, we found that 145-2C11 induces a profound hypothermia maximal between 3 h and 6 h after the injection (at 3 h: -3.0 +/- 0.1 degrees C) as well as hypoglycemia (blood glucose levels at 6 h and 24 h: 76 +/- 13 mg/100 ml and 92 +/- 22 mg/100 ml, respectively, p less than 0.001 as compared with control values). These metabolic changes are preceded by the release of TNF into the circulation (peak serum TNF levels at 2 h: 50 +/- 23 pg/ml, p less than 0.01 as compared with controls). The release of TNF induced by 145-2C11 depends on the effect of the mAb on T cells as it is not observed in athymic nude mice while lipopolysaccharide-resistant C3H/HeJ mice also display a significant rise in serum TNF (peak levels at 2 h: 59 +/- 44 pg/ml). Pretreatment of DBA/2 mice with 12 mg of rabbit anti-murine TNF antibodies completely prevents the hypothermia while the hypoglycemia is significantly attenuated. Finally, F(ab')2 fragments of 145-2C11 induce only a transient hypoglycemia (blood glucose levels at 6 h: 109 +/- 14, p less than 0.001 as compared with controls) but neither hypothermia nor significant TNF release. We conclude that TNF is a major mediator of the acute metabolic changes induced by the intact form of 145-2C11.

Animals↗
PubMed1990

Prenatal diagnosis of intrapericardial teratoma.

A case of intrapericardial teratoma diagnosed by ultrasound before birth is described. Planning for delivery and immediate neonatal intensive management allowed successful cardiac surgery, full resection of the tumour and full recovery.

Adult↗
PubMed1990

Dopamine dependence in hypocalcemic patients.

Two patients admitted for decompensated chronic obstructive pulmonary disease developed arterial hypotension requiring the prolonged infusion of dopamine. They had no sign of acute circulatory failure and their blood lactate levels were normal. In the two patients, the correction of unsuspected hypocalcemia allowed the rapid discontinuation of the dopamine infusion.

Aged↗
PubMed1988

Determination of glucose-6-phosphatase activity using the glucose dehydrogenase-coupled reaction.

We present a method to determine glucose 6-phosphate activity. This assay measures the rate of glucose released in the glucose-6-phosphatase reaction. The glucose is oxidized to beta-D-gluconolactone by glucose dehydrogenase in a coupled reaction that uses NAD(P)+. The determination is rapid, reproducible, and does not require withdrawal, precipitation, centrifugation, or neutralization steps. This method provides a simple resolution to the problem of the nonspecific appearance of Pi, which is especially important in studies of regulation of glucose-6-phosphatase performed in the presence of ATP.

Animals↗
PubMedDate not supplied

Rule-based versus associative processes in derivational morphology.

The present article examines whether derivational morphology shows evidence of an associative memory structure. A distributional analysis of stems of attested derivational forms revealed evidence of clustering around phonological properties (gangs) for all nonneutral affixes but only a few neutral affixes. Subjects' acceptability ratings for novel complex words revealed sensitivity to the gang structure associated with the relevant derivational affixes. Results suggest that, like inflectional morphology, derivational morphology shows dissociations between rule-based and associative generalization mechanisms.

Cognition↗
PubMedDate not supplied

Is there a dual system for regular inflections?

A central question in morphological research is whether there are whole-word representations for regularly inflected forms. A series of four lexical decision experiments addressed this question by looking at whole-word frequency effects across a range of frequency values with constant stem-cluster frequencies. Frequency effects were only found for inflected forms above a threshold of about 6 per million, whereas such effects were found for morphologically simple controls in all frequency ranges. We discuss these data in the context of two kinds of dual models and in relation to competition models proposed within the connectionist literature.

Cognition↗
PubMedDate not supplied

[Prevalence of smoking, awareness and evaluation of cessation methods amongst medical students].

This work describes and analyses the prevalence of smoking amongst medical students, their awareness of the methods of smoking cessation and the effectiveness they attribute to these methods and to medical advice. A questionnaire was distributed to students of medicine at the University of Navarra with open questions on the methods of smoking cessation of which they were aware, the effectiveness attributed to each of these and the effectiveness attributed to medical advice. Information was also gathered on: sex, year of study, smoking habit, average number of cigarettes smoked per day and the length of exposure to tobacco. Of 480 valid interviews, the prevalence of active smokers was 27.5% (CI 95%: 23.5-31.9); 4.2% ex-smokers and 68.3% who had never smoked. 42.7% named nicotine patches as a method of cessation and 25.2% nicotine chewing gum. With respect to the effectiveness attributed to each method, a median and interquartile range (IQR) of 20% (0-50) for the nicotine patches, 10% (0-40) for nicotine chewing gum and 20% (1-50) for medical advice. The more senior students and those that had been smoking for longer mentioned nicotine patches more frequently; more women than men knew about nicotine chewing gum. The senior students attributed greater effectiveness to nicotine patches. A future reduction is predicted in the number of active smokers in the medical sector. Amongst medical students the effectiveness of medical advice is overestimated. It is necessary to increase awareness of the methods for smoking cessation amongst medical students.

English Abstract↗
PubMedDate not supplied

[Clinical relevance of periodic limb movements during sleep in obstructive sleep apnea patients].

INTRODUCTION: The periodic limb movements disorder (PLMD) is frequently associated with the obstructive sleep apnea syndrome (OSAS), but the prevalence and clinical relevance of this association have not been studied in detail. OBJECTIVE: The objectives were to make a prospective study on the prevalence of PLMD in patients with OSAS, and correlate this association with clinical and respiratory parameters. PATIENTS AND METHODS: Forty-two patients diagnosed with OSAS, without clinical suspicion of PLMD, underwent a polysomnographic study. Clinical symptoms and signs were evaluated with an structured questionnaire, and respiratory parameters were obtained from the nocturnal study. RESULTS: Periodic limb movements were found in 10 patients (24%). There were no differences in clinical parameters between both groups (with and without periodical limb movements). However, respiratory parameters were significantly worse in patients without PLMD. CONCLUSIONS: PLMD is very frequent in patients with OSAS, and can contribute to worsen clinical signs and symptoms in these patients independently from respiratory parameters.

Electrocardiography↗
PubMedDate not supplied

[Auditory brain stem potentials evoked by electrical stimulation of cochlear nuclei during central auditive implant setting].

INTRODUCTION: The implantation of a stimulator over the surface of the cochlear nuclei can provide a partial auditive capability to patients deaf due to a bilateral lesion of the 8th nerve. Intraoperative monitoring of short latency electrically-evoked potentials is useful to asses the correct positioning of the implant, specially when there are anatomical distortions. PATIENTS AND METHODS: Evoked potentials from two patients with type II neurofibromatosis were recorded during implantation surgery, using a blanker system to eliminate the stimulus artifact. RESULTS: In both cases, two-peak vertex-positive responses were obtained, with latencies between 0.4-0.5 and 1.2-1.4, respectively. This responses are similar to the most frequent response described. DISCUSSION: Intraoperative monitoring of electrically-evoked auditory brainstem responses is a useful technique to confirm the correct positioning of the cochlear stimulator. The study of the morphology of these responses can help to understand the mechanisms involved in the generation by the brainstem of the auditive evoked potentials. More experience on this subject is needed to establish a correlation between intraoperative results and postoperative stimulator function.

Adult↗
PubMedDate not supplied

[The role of cortical oscillatory activity in information processing mechanisms].

INTRODUCTION: Cortical oscillatory activity has been related recently to information processing mechanisms. Synchronization between different neuronal groups can explain how he different features of an object can be integrated into a single perception (binding), or how different muscular groups can be co-ordinated into a single movement. DEVELOPMENT: This paper reviews the knowledge up to date on the role of cortical oscillatory activity in perceptive binding and motor control. Also, the participation of alterations in cortical oscillatory activity in different neurological diseases (epilepsy, Parkinson's disease) is proposed, basing on available data. CONCLUSION: The study of the changes in cortical oscillatory activity (specially in the so-called gamma band 30-60 Hz) can contribute to current knowledge on the physiology and pathophysiology of the different cortical areas involved in perceptive and motor tasks.

Cerebral Cortex↗
PubMedDate not supplied

[The pathophysiological basis of dystonia].

OBJECTIVE: We review the mechanisms that may involved in the pathophysiology of dystonia. DEVELOPMENT: The role of basal ganglia, spinal and brainstem interneurons, and primary motor cortex in dystonia will be discussed. Abnormalities in the discharge pattern of internal pallidum or thalamus, secondary to basal ganglia disorders might be the cause of disbalance between excitatory and inhibitory mechanisms in motor cortex. Other factors such as excessive repetition of a movement or abnormal sensory afferent discharges may be participating in cortical reorganization. CONCLUSIONS: Overlapping of the cortical representation of dystonic muscles due to enlargement of cortical maps could explain overflow and co-contraction phenomena. The study of the exact role of these factors in each type of dystonia is a challenge for the future that opens the door for new therapeutic approaches.

Anti-Dyskinesia Agents↗
PubMedDate not supplied

[Postictal paralysis during video-EEG monitoring studies].

OBJECTIVE: To know the frequency of Todd s paralysis during the video EEG monitoring studies, to investigate in its pathophysiology, and to confirm its value to localise the epileptic focus. PATIENTS AND METHODS: We reviewed 114 monitoring studies, in 102 patients. RESULTS: Sixty patients had epileptic seizures. An obvious paresis was noted in four seizures of two patients (3 and 1, respectively). Both patients had frontal epilepsy. During the paralysis, in the first patient the EEG showed ictal discharges on the contralateral centrotemporal area. In the second patient, the EEG demonstrated slow waves in the contralateral frontal region. The ictal onset was contralateral to the paresis in all cases. No patient with pseudoseizures had paralysis. CONCLUSIONS: Postconvulsive paralysis are not frequent in video EEG monitoring studies. However, if present it points out to a contralateral seizure onset. In our series it happened in patients with frontal seizures. The EEG may help to clarify if it correspond to a true postictal phenomenon or to a ictal paralysis.

Adult↗
PubMedDate not supplied

[Ictal asystolia in the differential diagnosis of dizziness].

Frequently, epileptic seizures are accompanied by changes in the heart rate. They are usually transient and irrelevant for the patient's symptoms and the patient recorders his usually baseline rhythm in second or a few minutes. In this report we present a case of a patient diagnosed previously of epilepsy who presented episodes of dizziness and presyncope. During the video-EEG study we recorded one of these spells. The diagnosis of this spell was a focal seizure associated with asystole: the seizure was almost asymptomatic, and only when the asystole developed (40 seconds after the EEG ictal changes) the patient complained about dizziness. Recovery was fast, but treatment with pacemaker must be considered.

Diagnosis, Differential↗